Answer:Simple Covalent substance
Explanation:Simple covalent substance describes a substance that has a low melting point and poor electrical conductivity because:
(1)melting point :For the covalent bond and intermolecular force that are present in a simple covalent substance,energy is needed to break the forces of attraction present. In the simple covalent substance, little energy is needed because the intermolecular forces present are broken because they are weaker compared to the covalent bond present.
Therefore, when simple covalent substance melts,only the intermolecular forces are broken leaving only the covalent bond in the substance.
(2) poor conductivity: for a substance to conduct electricity,it must have charged particles which are free to move to and fro.
But in the simple covalent substance,there are no charged particles that can be separated due to the covalent bond present in simple covalent substance.
Answer:
280 N
Explanation:
Applying Newton's third second law of motion,
F = m(v-u)/t................... Equation 1
Where F = Magnitude of the average force on the ball during contact, v = final velocity of the ball, u = initial velocity of the ball, t = time of contact of the ball and the wall.
Note: Let the direction of the initial velocity of the ball be positive
Given: m = 4 kg, u = 3.0 m/s, v = -4.0 m/s (bounce off), t = 0.1 s
Substitute into equation 1
F = 4(-4-3)/0.1
F = 4(-7)/0.1
F = -28/0.1
F = -280 N.
Note: The negative sign tells that the force on the ball act in opposite direction to the initial motion of the ball
Answer:
1.The Sun is located at one of the foci of the planets' elliptical orbits.
2.The path of the planets around the Sun is elliptical in shape.
Explanation:
As per Kepler's law of planet motion we know that all planets revolve around the sun in elliptical path in such a way that position of Sun must be at one of the focii of the path
So all planets are in elliptical path always
Position of sun is always at one of the focus
so correct answer will be
1.The Sun is located at one of the foci of the planets' elliptical orbits.
2.The path of the planets around the Sun is elliptical in shape.